Generally speaking, no, the swamp will sink people, because the soil in the swamp has a high water content, and the soil presents a fluffy state full of water, which can't bear too much pressure. Therefore, when people step on it, the structure of the soil will be destroyed, and it will naturally collapse downward. Moreover, the soil is rich in water, and its surface tension can firmly attract people, making it difficult for people to break free. But beach shoals are generally beaches, which are formed by seawater erosion and deposition. The density is relatively high and the water content is relatively low, so there is no such problem. However, beaches (usually of different colors) can't be trampled casually, and there is still the risk of being trapped.
But besides what you mentioned, there are other dangers at the seaside. If a person goes to the seaside without commercial development, it is better to go together. In case something happens, there is also a care. If the beach is a tourist attraction for commercial development, or many people go there, there is not much problem going alone.
Please adopt it if it is useful.